Effects of intraluminal nutrients on intestinal myoelectric activity in rabbits

Abstract

In the unanesthetized rabbit, intraluminal infusions of D- and L-methionine, L-tryptophan, D-glucose, D-xylose, and lactulose had a biphasic effect on small intestinal myoelectric activity. A phase of enhanced activity was followed by a phase of inhibition. The excitatory phase was mimicked by saline solutions equiosmolar to the test solutions. The subsequent inhibition was does dependent and significantly (P less than 0.01) longer for the passively absorbed D-methionine than for the L-stereoisomer. The inhibitory action of 10 mM D-glucose, 10 mM L-methionine, and 5 mM L-tryptophan was blocked by propranolol on the jejunum and by phenoxybenzamine on the ileum. We conclude that the initial excitatory phase induced by luminal amino acids and sugars may be dependent on an action on osmoreceptors, whereas the subsequent inhibitory phase may involve the sympathetic noradrenergic system.

Local inhibitory reflexes excited by mucosal application of nutrient amino acids in guinea pig jejunum

“…This was surprising since L-phenylalanine and L-tryptophan release CCK from the mucosa (50,71). However, the concentrations used here were lower (1 mM) than those used in previous studies (up to 50 mM) of activation of extrinsic afferents (51), intestinal motility (13,17), and CCK release (50,71). Thus, the intestine may be exposed to a range of concentrations of amino acids that activate local reflexes during the digestive process.…”

Divergent effect of saline and glucose solutions on myoelectric and motor activity of canine small bowel

“…Effect of hyperosmolar NaCl and glucose solutions infused in Phase I and I1 on electrical and motor activity of the small bowel infusions of each test solution was done, (range[13][14][15][16][17][18][19][20][21][22][23][24]. During all the studies slow waves were continuously NaCl(l250 mOsm/kg) recorded.…”